scholarly journals A new CF-IRMS system for quantifying stable isotopes of carbon monoxide from ice cores and small air samples

2010 ◽  
Vol 3 (5) ◽  
pp. 1307-1317 ◽  
Author(s):  
Z. Wang ◽  
J. E. Mak
Keyword(s):  
Carbon Monoxide ◽  
Stable Isotopes ◽  
Ice Core ◽  
Isotope Analysis ◽  
Ice Cores ◽  
Isotope Ratio Mass Spectrometry ◽  
Vacuum Extraction ◽  
Air Samples ◽  
Mixing Ratios ◽  
Core Samples

Abstract. We present a new analysis technique for stable isotope ratios (δ13C and δ18O) of atmospheric carbon monoxide (CO) from ice core samples. The technique is an online cryogenic vacuum extraction followed by continuous-flow isotope ratio mass spectrometry (CF-IRMS); it can also be used with small air samples. The CO extraction system includes two multi-loop cryogenic cleanup traps, a chemical oxidant for oxidation to CO2, a cryogenic collection trap, a cryofocusing unit, gas chromatography purification, and subsequent injection into a Finnigan Delta Plus IRMS. Analytical precision of 0.2‰ (±1δ) for δ13C and 0.6‰ (±1δ) for δ18O can be obtained for 100 mL (STP) air samples with CO mixing ratios ranging from 60 ppbv to 140 ppbv (~268–625 pmol CO). Six South Pole ice core samples from depths ranging from 133 m to 177 m were processed for CO isotope analysis after wet extraction. To our knowledge, this is the first measurement of stable isotopes of CO in ice core air.

scholarly journals A new CF-IRMS system for the quantification of the stable isotopes of carbon monoxide from ice cores and small air samples

2009 ◽  
Vol 2 (5) ◽  
pp. 2689-2705
Author(s):  
Z. Wang ◽  
J. E. Mak
Keyword(s):  
Carbon Monoxide ◽  
Ice Core ◽  
Isotope Analysis ◽  
Ice Cores ◽  
Isotope Ratios ◽  
Vacuum System ◽  
Vacuum Extraction ◽  
Air Samples ◽  
Core Samples ◽  
Cryogenic Vacuum

Abstract. A new simultaneous analysis technique for stable isotope ratios (δ13C and δ18O) of atmospheric carbon monoxide (CO) from ice core samples and small air samples is presented, based on an on-line cryogenic vacuum extraction followed by continuous-flow isotope ratio mass spectrometry (CF-IRMS). The CO extraction system includes two multi-loop cryogenic cleanup traps, a chemical oxidant for oxidation to CO2, a cryogenic collection trap, a cryofocusing unit, purification by gas chromatography, and subsequent injection into a Finnigan Delta Plus IRMS. Analytical precision of 0.2‰(±1σ) for δ13C and 0.6‰(±1σ) for δ18O can be obtained for 100 mL (STP) air sample with CO mixing ratio ranging from 60 to 140 ppbv (~268–625 pmol CO). Six South Pole ice core samples with depth ranging from 133 to 177 m are also processed for CO isotope analysis based on a wet extraction line attached to the above cryogenic vacuum system. This is the first report on measuring isotope ratios of CO in ice core samples.

scholarly journals Post-coring entrapment of modern air in polar ice cores collected near the firn-ice transition: evidence from CFC-12 measurements in Antarctic firn air and shallow ice cores

2010 ◽  
Vol 10 (1) ◽  
pp. 1631-1657 ◽  
Author(s):  
M. Aydin ◽  
S. A. Montzka ◽  
M. O. Battle ◽  
M. B. Williams ◽  
W. De Bruyn ◽  
...  
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Trace Gas ◽  
Gas Composition ◽  
Physical Processes ◽  
Polar Ice ◽  
Air Samples ◽  
Mixing Ratios ◽  
Core Samples ◽  
History Of

Abstract. In this study, we report the first measurements of CFC-12 (CCl2F2) in air extracted from shallow ice cores along with firn air CFC-12 measurements from three Antarctic sites. The firn air data are consistent with the known atmospheric history of CFC-12. In contrast, the ice core samples collected near the firn-ice transition exhibit anomalously high CFC-12 levels. Together, the ice core and firn air data provide evidence for presence of modern air entrapped in shallow ice core samples. We propose that this is due to closure of open pores after drilling, entrapping modern air and resulting in elevated CFC-12 mixing ratios. Our measurements reveal the presence of open porosity below the depth at which firn air samples can be collected and demonstrate how the composition of bubble air in shallow ice cores can be altered during the post-drilling period through purely physical processes. These results have implications for investigations involving trace gas composition of bubbles in shallow ice cores.

scholarly journals Post-coring entrapment of modern air in some shallow ice cores collected near the firn-ice transition: evidence from CFC-12 measurements in Antarctic firn air and ice cores

2010 ◽  
Vol 10 (11) ◽  
pp. 5135-5144 ◽  
Author(s):  
M. Aydin ◽  
S. A. Montzka ◽  
M. O. Battle ◽  
M. B. Williams ◽  
W. J. De Bruyn ◽  
...  
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Trace Gas ◽  
Gas Composition ◽  
Accumulation Rates ◽  
Physical Processes ◽  
Air Samples ◽  
Mixing Ratios ◽  
Core Samples ◽  
History Of

Abstract. In this study, we report measurements of CFC-12 (CCl2F2) in firn air and in air extracted from shallow ice cores from three Antarctic sites. The firn air data are consistent with the known atmospheric history of CFC-12. In contrast, some of the ice core samples collected near the firn-ice transition exhibit anomalously high CFC-12 levels. Together, the ice core and firn air data provide evidence for the presence of modern air entrapped in the shallow ice core samples that likely contained open pores at the time of collection. We propose that this is due to closure of the open pores after drilling, entrapping modern air and resulting in elevated CFC-12 mixing ratios. Our results reveal that open porosity can exist below the maximum depth at which firn air samples can be collected, particularly at sites with lower accumulation rates. CFC-12 measurements demonstrate that post-drilling closure of open pores can lead to a change in the composition of bubble air in shallow ice cores through purely physical processes. The results have implications for investigations involving trace gas composition of bubbles in shallow ice cores collected near the firn-ice transition.

Atmospheric history of carbon monoxide since preindustrial times reconstructed from multiple Greenland ice cores

2021 ◽  
Author(s):  
Xavier Faïn ◽  
Rachael Rhodes ◽  
Philip Place ◽  
Vasilii Petrenko ◽  
Kévin Fourteau ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
High Resolution ◽  
Ice Core ◽  
Ice Cores ◽  
Snow Accumulation ◽  
Absolute Calibration ◽  
Chemical Compositions ◽  
Accumulation Rates ◽  
Mixing Ratios ◽  
Enhanced Absorption

<p>Carbon monoxide (CO) is a regulated pollutant and one of the key components determining the oxidizing capacity of the atmosphere. Obtaining a reliable record of atmospheric CO mixing ratios since pre-industrial times is necessary to evaluate climate-chemistry models in conditions different from today. We present high-resolution measurements of CO mixing ratios from ice cores drilled at five different sites on the Greenland ice sheet which experience a range of snow accumulation rates, mean surface temperatures, and different chemical compositions. An optical-feedback cavity-enhanced absorption spectrometer (OF-CEAS) was coupled to continuous melter systems and operated during four analytical campaigns conducted between 2013 and 2019. The CFA-based CO measurements exhibit excellent external precision (ranging 3.3 - 6.6 ppbv, 1σ), and achieve consistently low blanks (ranging from 4.1±1.2 to 12.6±4.4 ppbv). Good accuracy and absolute calibration of CFA-based CO records enable paleo-atmospheric interpretations. The five CO records all exhibit variability in CO mixing ratios that is too large and rapid to reflect past atmospheric mixing ratio changes. Complementary tests conducted on discrete ice samples demonstrate that such patterns are not related to the analytical process (i.e., production of CO from organics in the ice during melting), but very likely are related to in situ CO production within the ice before analyses. Evaluation of signal resolution and co-investigation of high-resolution records of CO and TOC show that past atmospheric CO concentration can be extracted from the records’ baselines at four sites with accumulation rates higher than 20 cm water equivalent per year (weq yr<sup>-1</sup>). However, such baselines should be taken as upper bounds of past atmospheric CO burden. CO records from four sites are combined to produce a multisite average ice core reconstruction of past atmospheric CO for the Northern Hemisphere high latitudes, covering the period from 1700 to 1957 CE. From 1700 to 1875 CE, this record reveals stable or slightly increasing values remaining in the 100-115 ppbv range. From 1875 to 1957 CE, the record indicates a monotonic increase from 114±4 ppbv to 147±6 ppbv. The ice-core multisite CO record exhibits an excellent overlap with the atmospheric CO record from Greenland firn air which span the 1950-2010 time period. The combined ice-core and firn air CO history, spanning 1700-2010 CE, largely exhibits patterns that are consistent with the recent anthropogenic and biomass burning CO emission inventories. This brand new time series will be compared with the most recent results from Earth System Models involved in the CMIP6-AerChemMIP multi-model exercise.</p>

scholarly journals A sublimation technique for high-precision measurements of δ<sup>13</sup>CO<sub>2</sub> and mixing ratios of CO<sub>2</sub> and N<sub>2</sub>O from air trapped in ice cores

2011 ◽  
Vol 4 (2) ◽  
pp. 1853-1892 ◽  
Author(s):  
J. Schmitt ◽  
R. Schneider ◽  
H. Fischer
Keyword(s):  
High Precision ◽  
Ice Core ◽  
Stable Carbon Isotope ◽  
Ice Cores ◽  
Glass Tube ◽  
Isotope Ratio Mass Spectrometry ◽  
Vacuum Sublimation ◽  
Mixing Ratios ◽  
Trapped Air ◽  
Organic Sample

Abstract. In order to provide high precision stable carbon isotope ratios (δ13CO2 or δ13C on CO2) from small bubble and clathrate ice core samples we developed a new method based on vacuum sublimation extraction of the CO2 and gas chromatography-isotope ratio mass spectrometry (GC-IRMS). In a first step the trapped air is quantitatively released from ~30 g of ice and CO2 together with N2O are separated from the bulk air components and stored in a miniature glass tube. In an off-line step, the extracted sample is introduced into a helium carrier flow using a minimised tube cracker device. Prior to measurement, N2O and organic sample contaminants are gas chromatographically separated from CO2. Pulses of a CO2/N2O mixture are admitted to the tube cracker and follow the path of the sample through the system. This allows an identical treatment and comparison of sample and standard peaks. The ability of the method to reproduce δ13C from bubble and clathrate ice is verified on different ice cores. We achieve reproducibilities for bubble ice between 0.05‰ and 0.07‰ and for clathrate ice between 0.05‰ and 0.09‰ (dependent on the ice core used). A comparison of our data with measurements on bubble ice from the same ice core but using a mechanic extraction device shows no significant systematic offset. In addition to δ13C, the CO2 and N2O mixing ratios can be volumetrically derived with a precision of 2 ppmv and 8 ppbv, respectively.

scholarly journals High precision dual-inlet IRMS measurements of the stable isotopes of CO<sub>2</sub> and the N<sub>2</sub>O/CO<sub>2</sub> ratio from polar ice core samples

2014 ◽  
Vol 7 (7) ◽  
pp. 6529-6564 ◽  
Author(s):  
T. K. Bauska ◽  
E. J. Brook ◽  
A. C. Mix ◽  
A. Ross
Keyword(s):  
Isotopic Composition ◽  
Water Vapor Pressure ◽  
Ice Core ◽  
Ice Cores ◽  
Spectrometric Method ◽  
Mass Spectrometric Method ◽  
Polar Ice ◽  
Mixing Ratios ◽  
Core Samples ◽  
Oxygen Isotopic

Abstract. An important constraint on mechanisms of past carbon cycle variability is provided by the stable isotopic composition of carbon in atmospheric carbon dioxide (δ13C-CO2) trapped in polar ice cores, but obtaining very precise measurements has proven to be a significant analytical challenge. Here we describe a new technique to determine the δ13C of CO2 at exceptional precision, as well as measuring the CO2 and N2O mixing ratios. In this method, ancient air is extracted from relatively large ice samples (~ 400 grams) with a dry-extraction "ice-grater" device. The liberated air is cryogenically purified to a CO2 and N2O mixture and analyzed with a micro-volume equipped dual-inlet IRMS (Thermo MAT 253). The reproducibility of the method, based on replicate analysis of ice core samples, is 0.02‰ for δ13C-CO2 and 2 ppm and 4 ppb for the CO2 and N2O mixing ratios, respectively (1-sigma pooled standard deviation). Our experiments show that minimizing water vapor pressure in the extraction vessel by housing the grating apparatus in a ultra-low temperature freezer (−60 °C) improves the precision and decreases the experimental blank of the method. We describe techniques for accurate calibration of small samples and the application of a mass spectrometric method based on source fragmentation for reconstructing the N2O history of the atmosphere. The oxygen isotopic composition of CO2 is also investigated, confirming previous observations of oxygen exchange between gaseous CO2 and solid H2O within the ice archive. These data offer a possible constraint on oxygen isotopic fractionation during H2O and CO2 exchange below the H2O bulk melting temperature.

scholarly journals Online technique for isotope and mixing ratios of CH<sub>4</sub>, N<sub>2</sub>O, Xe and mixing ratios of organic trace gases on a single ice core sample

2014 ◽  
Vol 7 (8) ◽  
pp. 2645-2665 ◽  
Author(s):  
J. Schmitt ◽  
B. Seth ◽  
M. Bock ◽  
H. Fischer
Keyword(s):  
Nitrous Oxide ◽  
Trace Gases ◽  
Ice Core ◽  
Ice Cores ◽  
Isotope Ratios ◽  
Trace Gas ◽  
Vacuum Extraction ◽  
Data Set ◽  
Mixing Ratios ◽  
Organic Trace

Abstract. Firn and polar ice cores enclosing trace gas species offer a unique archive to study changes in the past atmosphere and in terrestrial/marine source regions. Here we present a new online technique for ice core and air samples to measure a suite of isotope ratios and mixing ratios of trace gas species on a single sample. Isotope ratios are determined on methane, nitrous oxide and xenon with reproducibilities for ice core samples of 0.15‰ for δ13C–CH4, 0.22‰ for δ15N–N2O, 0.34‰ for δ18O–N2O, and 0.05‰ per mass difference for δ136Xe for typical concentrations of glacial ice. Mixing ratios are determined on methane, nitrous oxide, xenon, ethane, propane, methyl chloride and dichlorodifluoromethane with reproducibilities of 7 ppb for CH4, 3 ppb for N2O, 70 ppt for C2H6, 70 ppt for C3H8, 20 ppt for CH3Cl, and 2 ppt for CCl2F2. However, the blank contribution for C2H6 and C3H8 is large in view of the measured values for Antarctic ice samples. The system consists of a vacuum extraction device, a preconcentration unit and a gas chromatograph coupled to an isotope ratio mass spectrometer. CH4 is combusted to CO2 prior to detection while we bypass the oven for all other species. The highly automated system uses only ~ 160 g of ice, equivalent to ~ 16 mL air, which is less than previous methods. The measurement of this large suite of parameters on a single ice sample is new and key to understanding phase relationships of parameters which are usually not measured together. A multi-parameter data set is also key to understand in situ production processes of organic species in the ice, a critical issue observed in many organic trace gases. Novel is the determination of xenon isotope ratios using doubly charged Xe ions. The attained precision for δ136Xe is suitable to correct the isotopic ratios and mixing ratios for gravitational firn diffusion effects, with the benefit that this information is derived from the same sample. Lastly, anomalies in the Xe mixing ratio, δXe/air, can be used to detect melt layers.

scholarly journals High-precision dual-inlet IRMS measurements of the stable isotopes of CO<sub>2</sub> and the N<sub>2</sub>O / CO<sub>2</sub> ratio from polar ice core samples

2014 ◽  
Vol 7 (11) ◽  
pp. 3825-3837 ◽  
Author(s):  
T. K. Bauska ◽  
E. J. Brook ◽  
A. C. Mix ◽  
A. Ross
Keyword(s):  
Isotopic Composition ◽  
High Precision ◽  
Water Vapor Pressure ◽  
Ice Core ◽  
Ice Cores ◽  
Mass Spectrometric Method ◽  
Polar Ice ◽  
Mixing Ratios ◽  
Core Samples ◽  
Oxygen Isotopic

Abstract. An important constraint on mechanisms of past carbon cycle variability is provided by the stable isotopic composition of carbon in atmospheric carbon dioxide (δ13C-CO2) trapped in polar ice cores, but obtaining very precise measurements has proven to be a significant analytical challenge. Here we describe a new technique to determine the δ13C of CO2 at very high precision, as well as measuring the CO2 and N2O mixing ratios. In this method, ancient air is extracted from relatively large ice samples (~400 g) with a dry-extraction "ice grater" device. The liberated air is cryogenically purified to a CO2 and N2O mixture and analyzed with a microvolume-equipped dual-inlet IRMS (Thermo MAT 253). The reproducibility of the method, based on replicate analysis of ice core samples, is 0.02‰ for δ13C-CO2 and 2 ppm and 4 ppb for the CO2 and N2O mixing ratios, respectively (1σ pooled standard deviation). Our experiments show that minimizing water vapor pressure in the extraction vessel by housing the grating apparatus in a ultralow-temperature freezer (−60 °C) improves the precision and decreases the experimental blank of the method to −0.07 ± 0.04‰. We describe techniques for accurate calibration of small samples and the application of a mass-spectrometric method based on source fragmentation for reconstructing the N2O history of the atmosphere. The oxygen isotopic composition of CO2 is also investigated, confirming previous observations of oxygen exchange between gaseous CO2 and solid H2O within the ice archive. These data offer a possible constraint on oxygen isotopic fractionation during H2O and CO2 exchange below the H2O bulk melting temperature.

scholarly journals Online technique for isotope and mixing ratios of CH<sub>4</sub>, N<sub>2</sub>O, Xe and mixing ratios of organic trace gases on a single ice core sample

2014 ◽  
Vol 7 (3) ◽  
pp. 2017-2069 ◽  
Author(s):  
J. Schmitt ◽  
B. Seth ◽  
M. Bock ◽  
H. Fischer
Keyword(s):  
Nitrous Oxide ◽  
Trace Gases ◽  
Ice Core ◽  
Ice Cores ◽  
Isotope Ratios ◽  
Small Sample ◽  
Trace Gas ◽  
Vacuum Extraction ◽  
Mixing Ratios ◽  
Organic Trace

Abstract. Polar ice cores enclosing trace gas species offer a unique archive to study changes in the past atmosphere and in terrestrial/marine source regions. Here we present a new online technique for ice core and air samples to measure a suite of isotope ratios and mixing ratios of trace gas species on a single small sample. Isotope ratios are determined on methane, nitrous oxide and xenon with reproducibilities for ice core samples of 0.15‰ for δ13C-CH4, 0.22‰ for δ15N-N2O, 0.34 ‰ for δ18O-N2O, and 0.05‰ for δ136Xe. Mixing ratios are determined on methane, nitrous oxide, xenon, ethane, propane, methyl chloride and dichloro-difluoromethane with reproducibilities of 7 ppb for CH4, 3 ppb for N2O, 50 ppt for 136Xe, 70 ppt for C2H6, 70 ppt for C3H8, 20 ppt for CH3Cl, and 2 ppt for CCl2F2. The system consists of a vacuum extraction device, a preconcentration unit and a gas chromatograph coupled to an isotope ratio mass spectrometer. CH4 is combusted to CO2 prior to detection while we bypassed the oven for all other species. The highly automated system uses only ~160 g ice, equivalent to ~16 mL air, which is less than previous methods. This large suite of parameters on a single ice sample is new and helpful to study phase relationships of parameters which are usually not measured together. A multi-parameter dataset is also key to understand in situ production processes of organic species in the ice, a critical issue observable in many organic trace gases. Novel is the determination of xenon isotope ratios using doubly charged Xe ions. The attained precision for δ136Xe is suitable to correct the isotopic ratios and mixing ratios for gravitational firn effects, with the benefit that this information is derived from the same sample. Lastly, anomalies in the Xe mixing ratio, δXe/air, can be used to detect melt layers.

scholarly journals A sublimation technique for high-precision measurements of δ<sup>13</sup>CO<sub>2</sub> and mixing ratios of CO<sub>2</sub> and N<sub>2</sub>O from air trapped in ice cores

2011 ◽  
Vol 4 (7) ◽  
pp. 1445-1461 ◽  
Author(s):  
J. Schmitt ◽  
R. Schneider ◽  
H. Fischer
Keyword(s):  
High Precision ◽  
Ice Core ◽  
Stable Carbon Isotope ◽  
Ice Cores ◽  
Glass Tube ◽  
Isotope Ratio Mass Spectrometry ◽  
Mixing Ratios ◽  
Trapped Air ◽  
Organic Sample ◽  
Mechanical Extraction

Abstract. In order to provide high precision stable carbon isotope ratios (δ13CO2 or δ13C of CO2) from small bubbly, partially and fully clathrated ice core samples we developed a new method based on sublimation coupled to gas chromatography-isotope ratio mass spectrometry (GC-IRMS). In a first step the trapped air is quantitatively released from ~30 g of ice and CO2 together with N2O are separated from the bulk air components and stored in a miniature glass tube. In an off-line step, the extracted sample is introduced into a helium carrier flow using a minimised tube cracker device. Prior to measurement, N2O and organic sample contaminants are gas chromatographically separated from CO2. Pulses of a CO2/N2O mixture are admitted to the tube cracker and follow the path of the sample through the system. This allows an identical treatment and comparison of sample and standard peaks. The ability of the method to reproduce δ13C from bubble and clathrate ice is verified on different ice cores. We achieve reproducibilities for bubble ice between 0.05 ‰ and 0.07 ‰ and for clathrate ice between 0.05 ‰ and 0.09 ‰ (dependent on the ice core used). A comparison of our data with measurements on bubble ice from the same ice core but using a mechanical extraction device shows no significant systematic offset. In addition to δ13C, the CO2 and N2O mixing ratios can be volumetrically derived with a precision of 2 ppmv and 8 ppbv, respectively.

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